The present invention relates to a method and apparatus for optically recognizing code information, and more particularly to one in which the distance between a converging lens and a light responsive image sensor is adjusted automatically.
Information recognizing systems are known well in the art. According to one of these systems, an illumination light is supplied to a bar code to be reflected, and the reflected light is converged and received by a converging lens and a light responsive image sensor, respectively, which are optically coupled with each other. Since the reflected light has a light density corresponding to the light reflectivity of the bar code, the bar code is converted by the image sensor into an image signal which has a signal level corresponding to the density of reflected light. This image signal is then processed electrically for recognizing the bar code.
It has been a great disadvantage, however, that the image sensor is often unable to produce a correct image signal due to reflected light which is not clear in contrast. This drawback occurs when, for example, the converging lens is positioned too far from the bar code or the light responsive image sensor is positioned too far from the converging lens. In these occasions, it is necessary that clear reflected light is received by the light responsive image sensor through the converging lens so that the bar code is recognized correctly.